Unrelated to software but the company my dad works for (motor repair) has to buy all its parts from its own distribution arm, at the marked up price. He then has to turn a profit on those parts as well as pricing the labour.

If cost price is £5 and the markup is 20%, he has to pay £6 to get the part, then charge £7.20 on the invoice to the customer. I’ll let you guess what that does to tender bids ;-)